Oxypropylated esters of sulfopolycarboxylic acids



Patented May 25, 1954 OXYBRQPYLATED ES'IEERSW OE' SULEOF I PQLYEARBOXY-LIG- ACIDS; Mlyi'nD'e' Groote; University City, Moz, assi'gnor toPetrolite Corporation, a-corporation'ofiDela N aDrawing; Application J anuary 29,1951;

They present" invention: is" concerned" with certainhnew products; compounds or 'compositions of matterywhich are essentially mixed ester salts of La; monobasiir acid. and? a" p'olybasic acid. Two moles of the former and; more specifically,- monocarboxy acids. are employed whereas one-mole of the, latter, is; employed. The: latter; is a typein which, 3 carboxyl. radicals appear: and onesulfo radical? Thecarlioxylradicals appear-in= ester form and the sulfo radical in salt form. Such compounds are derived preferably by reaction. between four types of reagents; (a) polypropylene glycol of a molecular weight sufiicient tozgive water-insolubility and kerosene-solubility, generally being in the molecular weight range of750, to approximately 3,000; (b) citraconic acid a low molal monocarboxy acid having less than 8- carbon atoms and preferably 3 or less; and (d): an alkali metal bisulfite such as sodium bisulfite or potassium bisulfite.

The present invention is a continuation-in-part of my copending application, Serial No. 186,685; filed September 25, 1950, now Patent 2,602,058:

The preparation of the compounds or products previously described involves substantially three steps; (a) the esterification of the propylenegly col mole for mole with the low molal monocarboxy acid, such as acetic acid, propionic; acid; lactic acid, etc., to produce a fractional ester-having one free hydroxyl radical; (b) esterification between two moles of the fractional ester obtained from polypropylene glycol and aconitic acid; andli (c) reaction between such complete esterz-anda.

I suitable alkali metal bisulfite such as sodium:

More specifically the present inventionis 0011+ cerned with certain hydrophile products; said by. drophile synthetic products being characterized I by the following formula:

II V or ooimlinioicRf i is included in thelhereto. attached-iclaims'as the obviouschemical equivalent. Similarly, ammonium bisulfite may be employed instead of "sodium or-potassium-bisulfite.- This-appliesralsoto-abisulfite of various. organic. bases provided. of course, that; such casespriortd'forming.a sulfite are as basic as ammonialandi that thesulfiteis water-soluble. All these; arethe obvious funcational equivalents r of sodium. bisulfitezv Thezproa cedure is illustrated bythefollowing:example-z EXAMPLE In a reaction flasli there were placed 9.6 grams of'glacial'acetic'acid; and"325-grams-of-propylene glycol.2025. (molah'atio of glycol to acid 1:1 along with one-half ofione'percent of toluene sulfonic a'cidi. In this instance 1:6 grains" were used.

There were also added 50 c. c. of xylene. Heat was applied and the mixture allowed to reflux for about 3 hours. The: maximum temperature during the reflux: periodwas145 C. At theend ofgthis time lessthan 3 c'..c. of water'was'carried over to the phase-separating trap, Similarly, atathe end of this periodsthere' wasstill a slight acidity due to the catalyst and also due perhaps to a small amount of uncombined acetidacid. An additional one-half per cent of toluene sulfonic acid was; added; alongwitiifi grams of aconitic 'acid'; Heat-wasapplied and the mixture refluxed for four" hours: The maximum tam-*- perature' duringthe secondrefiux'period'; as" in the first; was' C." The amount ofwater which" distilled" over. inthis instance was about the same-asin theprevious-periodf At the end of thereaction' period there was still a: slight acidity due to'" the presence" of 'thea'cid catalyst and possibly some" uncombinedaconitic-acidj and possibly some uncombined acetic a'cidi A3 small amount 0f'30 aqueouscaustivsoda'wasadded until'sufiicient ha'dtb'een introduced to neutralize the freesulfonic'acid-radicalsand th'e free'car boxyl acid radicals:

After" this adjustment 6" g ams of powdered sodium bisulfitewereadded'. Apparently enough water had been added along with the caustic soda to dissolve at least part of the sodium bisulfite so that further addition of water was not required. Needless to say, if no caustic soda solution was added to neutralize the acidity then a little water should be added to dissolve at least part or all of the sodium bisulfite so as to give a saturated solution. The reaction mixture was stirred for three hours. No effort was made to have any reflux take place during this stage of the reaction for the obvious reason that if water were removed and the sodium bisulfite were anhydrous there would be little or no opportunity for reaction. This was necessary also for the reason that sodium bisulfite begins to decompose at about 100 C. and this reaction obviously must be conducted at a suitable temperature until the sodium bisulfite has combined. Thereafter the xylene can be distilled over in the usual manner, removing any water with it and all the xylene can be removed by distillation, particularly vacuum distillation.

The same procedure was followed in connection with a number of additional samples, all of which are illustrated in the following table which gives the reactants, amounts employed,

4 750 to 1,000 or 2,000 as the case may be and really represents a cogeneric mixture whose statistical average molecular weight is the one indicated. Reference in the table is, of course, to hydroxyl value molecular, weight for the obvious reason that this is the basis for calculating the amount of reactants required.

In all instances a small amount of caustic soda was used as in the more complete description of Example 1. Also a small amount of toluene sulfonic acid, approximately 1% of the weight of'the glycol or slightly less, was used in the two esterification steps. About one-half of this amount was used in the first esterification step (with the monocarboxy acid), and an equal amount added during the second esterification step (with the dicarboxy reactant). A larger amount should not be used at any time because there may be decomposition of the glycol. The total amount can be added during the initial esterification if desired. Smaller amounts can be used, for instance, a total of of 1% or of 1% based on the amount of glycol, provided, however, that the esterification time is extended somewhat.

One may use any one of a variety of monocarboxy acids, such as those previously noted,

temperature of esterification, etc. or higher acids of the aliphatic series, such as Table 1 Max M.W.of Ester- Ex. Polypro- Monocarboxy Xylene g i g' ification No pylene (gm) ,cid (grs) (ccm.) Temp Time glyc l 3 (hrs) 2,025 9.5 145 3% 725 9.5 50 13s 3% 1, 025 9.5 50 140 3 2,525 9.5 50 145 4 1,525 9.5 50 144 3% 2,02 12.3 50 145 4 725 12.3 50 13s 3 1,025 12.3 50 140 3% 2, 525 12. a 50 145 3% 1, 525 12. 3 50 13s 4% Table 2 Max Estenfi- Sodmm Max.Re- Reac- Ex. Dicarboxy 12 cation Bisulaction tion No Reactant (grs Temp Time fite Temp. Time a 0) (hrs.) (grs.) 0.) (hrs.)

9.3 145 3%, 5 30-95 3 9.3 140 3% 5 30- 4% 9.3 143 3 /5 5 30-95 3% 9.3 140 3% 5 80-95 3 9.3 135 4 9 80-95 344 9.3 141 4 9 80-95 444 9.3 131 3% 5 30-95 4 9.3 139 4 3 30-95 3% 9.3 140 3 /5 5 80-95 4 9.3 137 4 5 8095 4% Polypropylene glycols are commercially availm butyric or valeric. The acids may be cyclic as able. Such polypropylene glycols are furnished in the case of benzoic, cyclohexanoic and furoic. in various molecular weight ranges. The water- The acid may have t e Carbon Chain interrupted insoluble, kerosene-soluble polypropylene glycols begin in the molecular weight range somewhere above 500, and more specifically, at about I00 or 750. The molecular weight was usually determined by the hydroxyl method. Such hydroxyl molecular weight is a fraction sometimes a large major fraction, of the theoretical molecular weight based on the method of synthesis, 1. e., the calculated molecular weight based theoretically on the value one would expect to obtain by treating water or propylene glycol, for example, with propylene oxide. Needless to say, one does not obtain a single compound but a by an oxygen atom as in the instance of betamethoxy propionic acid. The acids may be hydroxylated as in the case of hydroxy-acetic acid or lactic acid. In any event, however, the acids must be free from any radical having 8 or more uninterrupted carbon atoms in a single group.

One need not prepare the ester in the manner described above but may use some other conventional procedures, as, for example, the use of the acyl chloride instead of the acid, or by alcoholysis involving methyl or ethyl acetate, ethyl or methyl propionate, etc. One may also start with the acid itself, such as acetic acid propylene glycol of a molecular weight ratio of or propionic acid and subject such acid to oxypropylation until the desired molecular weight is reached.

The products obtained are comparable to the initial glycol in appearance, etc., i. e., usually they are an amber color or at least of a slight straw color, and often somewhat thicker than the original glycol. This description, of course, applies to materials after removal of the solvent, i. e., the xylene. For use as demulsifiers there is no need to remove the xylene and it may remain behind. Obviously other liquids than xylene may be used in esterification procedure. However, if the boiling point is any higher than xylene there is danger that decomposition may take place unless the amount of sulfonic acid is reduced. Other catalysts such as a small amount of dry hydrochloric acid can be used but it appears less desirable than the sulfonic acid. Needless to say, the caustic soda solution used neutralizes the sulfonic acid catalyst present.

In the various examples preceding only one glycol has been used in these cases. Actually there is no reason why one may not use two dififerent glycols, for instance, an equimolar mixture of two glycols, one for example, having a molecular Weight of 2000 and the other 3000; or one having a molecular weight of 1500 and the other 2500. Actually these glycols are cogeneric mixtures at each selected molecular weight. Since aconitic acid has three carboxyls one could select glycols of three different molecular weights, for instance, 1500, 2250 and 3000. Momentarily one need only look at a simple situation, i. e., if maleic acid were employed, i. e., a compound having two carboxy radicals instead of three. In such event if one does make a mixture of the kind here described actually three types of compounds will appear, one type in which both dicarboxy acid radicals are joined with the higher glycol, one type where both carboxyls are joined with the lower molecular weight glycol, and one type where one carboxyl is united to a higher molecular weight glycol and the other one to a lower molecular weight glycol.

Other variations are obviously possible by using different monocarboxy acids. For example, the aconitic acid can be used united with different ferent acids might be joined to glycols of different molecular weights.

The products so obtained are peculiar (a) insofar that there is not present any radical having 8 or more uninterrupted carbon atoms, and (b) the compounds are not particularly efiective as surface-active agents in the ordinary sense due either to the large molecular size or the absence of a hydrophobe radical of the kind previously referred to, or for some other reason which is obscure. The chemical compounds herein employed as demulsifiers have molecular weights varying from 1500 up to several thousands, for instance, 6000, 7500 and 9000, and yet contain only one sulfo radical. Utility of such compounds for industrial uses is rather unusual. They are not efiective emulsifying agents, but are valuable as an additive or a promoter of emulsions. These compounds also have hydro-tropic property and serve as common solvents in the preparation of micellar solutions. It is to be noted that they are free from terminal carboxyl radicals and thus differ from reagents, obtained, for example, by treating one mole of a high molal polyropylene glycol with 2 moles of a dicarboxy acid.

As pointed out in aforementioned co-pending application, Serial No. 186,685, filed September 25, 1950, now Patent 2,602,058, products of the kind above described are suitable for demulsification of petroleum emulsions of the water-inoil type. Said aforementioned co-pending application is directly concerned with this phase of the invention. However, the utility of these compounds is not limited to this particular field of application but I have found they are useful for other purposes, such as the following, and particularly as additives in the preparation of emulsions. Extremely dilute emulsions, for instance, those in which the dispersed phase is less than two-tenths of a per cent, and usually less than one-tenth of a per cent, have been prepared without using an emulsifying agent. The majority of emulsions, however, are prepared by the use of an emulsifying agent, and thus the emulsion system consists essentially of three ingredients. However, many technical emulsions actually have a fourth ingredient which may be an emulsifier of indifferent or inferior effect, but is valuable because it is a coupling agent or mutual solvent. See The Composition and Structure of Technical Emulsions, J. H. Goodey, Royal Amtralian Chem. Inst. J. 8: Proc., 16, 1949, pp. 47-75.

Other uses involve these compounds as breakinducers in the doctor treatment of sour hydrocarbons, as additives to lubricating oils of both the naturally-occurring petroleum type of lubricant and also synthetic lubricants which in many instances are largely polymerized alkylene oxides as described in U. S. Patent No. 2,448,664, dated September 7, 1948, to Fife, et al.

Having thus described my invention what I claim as new and desire to secure by Letters Patent, is:

1. Hydrophile synthetic products; said hydrophile synthetic products being characterized by the following formula:

in which n is a whole number varying from 10 to OCR is the acyl radical of a low molal monocarboxy acid having less than 8 carbon atoms, and with the proviso that the polyoxypropylene glycol ether prior to esterification be water-insoluble and kerosene-soluble.

2. The product of claim 1 wherein the value of n is approximately 15.

3. The product of claim 1 wherein the value of n is approximately 25.

4. The product of claim 1 wherein the value of n is approximately 35.

5. The product of claim 1 wherein the value of n is approximately 45.

6. The product of claim 1 wherein the value of n is approximately 55.

References Cited in the file of this patent 

1. HYDROPHILE SYNTHETIC PRODUCTS; SAID HYDROPHILE SYNTHETIC PRODUCTS BEING CHARACTERIZED BY THE FOLLOWING FORMULA: 